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9 Cards in this Set

Control of microbial growth can aprevent infections and food spoilage.
Sterilaztion (destroying all microbial life on an object)
Heat of canned food to destroy C. botulisum endospores.
disinfection -forf nonliving surface
antisepsis to reduce or inhibitg microorganisms on living tissue.
suffix cide means to kill suffix stat means to inhibit
sepsis is bacterial contamination

factors influencing success of control methods

Number and Nature of microorganisms
The time it takes to kill a microbial pop. is proportional to the # of microbes.
Microbial species and life cycle phases eg. endospores have diff. susceptibilities to physical and chemical controls.
Organic matter may interfere with heat trts and chemical control agents.
Longer exposure to lower heat can produce the same effect as shorter time at higher heat.

strength of control agent

some microbial control agents damage cellular proteins by breaking hydrogen and covalent bonds.
other agents interfere with DNA and RNA replication and protein synthesis.

Time, temperature, and ph

heat, moist heat by denaturing enzymes.
Thermal death point TDP is lowest temp at which all the bacteria in a liquid cult. will be killed in 10 mins.
DRT Decimal reduction time is the length of time in which 90% of a bacterial population will be killed at a given temp.
boiling 100 C kills many vegatative cells and viruse with in 10 mins.
Autoclaving
pasteruization
Dry heat sterilization
Different methods that produce the same effect (reductiond in microbial growth) are called equivalent treatments.
Filtration
By air by high effeciencyh particulate air filters.
Membrane filters composed of nitrocellulose or cellulose acetate to filter out bacteria, viruses and large proteins.

cont

Desiccation- abscence of water, microorganisms cannot grow
Viruses and endospores can resist desiccaton
Osmotic pressure- Microorganisms in high concentrations of salts and sugars undergo plasmolysis.
Molds and yeasts are more capable than bacteria of growing in materials with low moisture or high osmotic pressure.
radiation

Conditions influencing microbial growth

chemical disinfectants is affected by the type of microorganism and the physical environment.

chemical methods of control

chemical agents are used on living tissue (antispectics and on inanimate objects disinfectants)